Step drill bit



FIG. 1 is a first side view of a step drill bit embodying the invention.

FIG. 2 is a second side view of the step drill bit of FIG. 1.

FIG. 3 is a third side view of the step drill bit of FIG. 1; and,

FIG. 4 is a fourth side view of the step drill bit of FIG. 1.

The broken lines in the drawings depict portions of the step drill bit which form no part of the claimed design. 

CLAIM We claim the ornamental design for a step drill bit, as shown and described. 